Trailing-blade-coater including adjustable drag-blade



P 1966 G. KRIKORIAN 3,273,535

TRAILING-BLADE-COATER INCLUDING ADJUSTABLE DRAG-BLADE Filed Oct. 6, 19645 Sheets-Sheet l Sept. 20, 1966 G. KRIKORIAN TRAILING-BLADE-COATERINCLUDING ADJUSTABLE DRAG-BLADE 5 Sheets-Sheet 2.

Filed Oct. 6, 1964 p 0, 1966 KRIKCRIAN 3,273,535

TRAILING-BLADE-COATEH INCLUDING ADJUSTABLE DRAG-BLADE Filed Oct. 6, 19645 Sheets-Sheet 5 United States Patent 3,273,535 TRAILING-BLADE-COATERINCLUDING ADJUSTABLE DRAG-BLADE Garo Krikorian, Paxton, Mass., assignorto Rice Barton Corporation, Worcester, Mass., a corporation ofMassachusetts Filed Oct. 6, 1964, Ser. No. 408,716 Claims. (Cl. 118-410)This application is a continuation-in-part of my prior application,United States Serial No. 206,378, filed June 29, 1962, for LiquidApplying Coaters and now abandoned.

The present invention relates to improvements in liquid applying coatersand more particularly to a drag blade for controlling the circulation ofthe liquid coating within the enclosure for said coating which isinduced by the rapid passage of the web through the liquid and therebyto establish a better control of thickness and uniformity of saidcoating.

The invention is disclosed in a preferred form as embodied in a trailingblade type coater in which the web is passed downwardly around a backingroll past a liquid coating enclosure and doctor blade assembly whichincludes an enclosure for liquid coating material having an open faceagainst said web and an enclosed rear face, and a doctor blade having aweb engaging edge enclosing the bottom of said enclosure. In theoperation of a coater of this general description, particularly when theweb is driven at high speeds, a condition of turbulence tends to be setup within the enclosure which tends to produce an uneven distribution ofthe coating with consequent streaking and spotting of the coated web.

It is a principal object of the invention to provide a novel andimproved device for controlling turbulence and any consequent tendencytoward uneven distribution, streaking or spotting of the coatingproduced by the passage of the web through the reservoir underconditions of high-speed operation.

It is a further object of the invention to provide a reliable, readilyadjustable means to accurately control the weight of the coatingdeposited on the traveling web.

With these and other objects in view as may hereinafter appear, afeature of the invention consists in the provision of a drag blade whichis of a length to extend across the web and supported to extend fromoutside beneath the surface of the liquid coating, said drag blade beinglocated adjacent the web at the point of entry of said web and dragblade into the liquid coating shielding the entering portion of the webfrom contact with the liquid coating and with the submerged inner edgeof the drag blade spaced from the doctor blade so that that portion onlyof the traveling web beneath the surface of the liquid extending fromsaid inner submerged edge of the drag blade to the leaving edge definedby the yieldable trailing edge of the doctor blade is in contact withthe liquid coating.

The drag blade may be formed of a heavy gage steel which is pre-shapedto conform accurately to the curvature of the backing roll supportedweb, or may be formed of a flexible or pliable material to be suspendedfrom above the reservoir adjacent the traveling web, so that the bladetends to be swayed and bent by the forces set up within the reservoir bythe rapidly moving web to a position adjacent to and with a contourwhich is conformed generally to the curvature of the traveling web.

When the drag blade is thus located with the lower portion thereofprojecting within the reservoir in a position closely adjacent thetraveling web the liquid coating is engaged only with a portion of thetraveling web below the liquid surface producing a smooth, even flow ofthe liquid Without turbulence or other disturbance. The eddy 3,273,535Patented Sept. 20, 1966 "ice currents thus set up tend to bend and tomold the blade against the Web, this tendency, however, being offset byan air suction set up between the traveling web and the blade which actsto support the blade in a narrowly spaced closely adjacent position withrelation to the web.

Another feature of the invention consists in the provision of means foradjusting the position of the drag blade in an upward and downwarddirection to vary the spacing of the lower immersed edge of the dragblade from the doctor blade closing the lower or leaving side of theopen face of the liquid coating enclosure.

The several features of the invention consist also in the devices,combinations and arrangement of parts hereinafter described and claimedwhich together with the advantages to be obtained thereby will bereadily understood by one skilled in the art from the followingdescription taken in connection with the accompanying drawings, inwhich:

FIG. 1 is a detail sectional view in side elevation of a trailing bladetype coater illustrating particularly the backing roll, the trailingdoctor blade and coating pond assembly in combination with a drag blademechanism, only so much of the machine having been shown as is believednecessary to show connection of the present invention therewith;

FIG. 2 is a plan view of substantially the parts shown in FIG. 1;

FIG. 3 is a view similar to FIG. 1 but with the drag blade in its raisedposition to illustrate the manner in which the increased loading andspringing of the doctor blade will increase the thickness of thecoating;

FIG. 4 illustrates a modified form of the invention in which the doctorblade and coating pond assembly are located directly beneath the backingroll and web;

FIG. 5 is a diagrammatic view illustrating an alternative form of theinvention in which a second roller is provided in place of the doctorblade and coating pond assembly for applying a coating to the web;

FIG. 6 is a somewhat diagrammatic sectional view in side elevationsimilar to previous figures in which an extremely thin and flexible dragblade is employed in a pressurized coating pond assembly;

FIG. 7 is a detail plan section takes on a line 77 of FIG. 6;

FIG. 8 is a detail fragmentary view similar to FIG. 6, but on a largerscale showing the drag blade in a more open or withdrawn position ofadjustment; and

FIG. 9 is a somewhat diagrammatic view similar to FIG. 7 in which aflexible drag blade is suspended within an open liquid coating containerapplied to a side of the backing roll and web traveling thereon.

Referring to FIG. 1 of the drawings, elements of a trailing blade typecoater are shown including a backing roll 20 around which a travelingweb 22 is drawn in a downward direction, and a coater head 24 whichhouses a liquid coating enclosure 26 and a doctor blade 28 mounted uponand closing the lower end of the enclosure 26. The coater head 24 isadjustably secured in position on supporting arms 30 which are attachedto the two ends of the coater head. The two ends of the enclosure 26 areclosed by means of dikes which may be of the general type indicated at32 in FIG. 2. In the present construction there is also provided a dragblade 34 which extends across the width of the web between the dikes 32and is curved as shown in cross section to conform substantially withthe curvature of the web passing around the backing roll 20. The dragblade 34 is secured at its upper edge to a tubular member 36 whichextends across the width of the backing roll 20. By way of contrast withthe disclosure of FIGS. 6 and 7, the blade 34 is assumedto be ofsufficient thickness to be self-supporting so that the desired curvatureis maintained independently of the hydraulic forces set up in the bathby the rapidly moving web.

The tubular member 36 is supported at each end by two identicalsupporting structures one of which is shown in FIGS. 1 and 2. Each ofthe two supporting structures referred to comprises an open ring bearing38 for the tubular member 36, said ring bearing 38 being formed on theprojecting end of a plunger 40 which is slidably mounted in a block 42rotatably supported on a cylindrical bar 46 which is secured to andforms an integral part of the color pond 24 and doctor blade 28assembly. As best shown in FIGS. 1 and 2 the rod 46 is rigidly clampedadjacent each end in a split clamp 48 forming part of the color pond 24assembly.

The supporting structures for the tubular member 36 and drag blade 34are constructed and arranged for angular adjustment about the rod 46 toeffect an up and down adjustment of the drag blade to control the widthof the traveling web area exposed to the coating material in the colorpond. A rotational adjustment of said supporting structure is employedto effect a corresponding forward and back adjustment of the plungers 40and drag blade 34, and also to maintain the contoured inner surface ofthe drag blade in narrowly spaced relation closely adjacent thetraveling web.

The plunger 40 is provided toward its rear end with a vertical slot 50which receives a relatively fixed vertically disposed cam plate 52, thelower end of which is formed with a lateral extension 54 bolted to therear face of the splint clamp 48. The rear edge of the cam plate 52 isformed with a cam surface 56 which is adapted for engagement with afollower roll 58 which extends across the rear end of the slot '50 inthe plunger 40. The cam plate 52 extending through the slot 50 acts tosupport the assembly including plunger 40 and block 42 against axialmovement on the rod 46. The cam surface 56 engaging roll 58 determinesthe forward and back position of the plunger, which is biased in aforward direction by means of a spring 60 coiled about the plungerbetween a collar 62 on the plunger and a recessed shoulder 64 in theblock 42. The contour of the cam 56 is such that rotata-tional movementof the block 42 and supported plunger 40 about the axis of shaft 46 Willeffect a corresponding forward or back movement of the shaft 40 whichcauses the tubular member 46 and drag blade 34 to be maintained for allangular adjustments of the supporting assembly closely adjacent thesurface of the web 22 and backing roll 20. The up and down adjustment ofthe drag blade assembly above described is accompanied by acorresponding angular adjustment of the shaft 36 and drag blade 34 sothat the lower edge of the drag blade is also maintained in its properposition closely adjacent the traveling web. To this end there issecured to the block 42 a plate 68 which is secured by screws 70 to oneside of the block 42 and which is provided with a forwardly and upwardlyextending arm 72 providing a cam surface which is engaged by a roller 74mounted on a short rearwardly extending post 76 secured to the tubularmember 36.

Each block 42 together with the associated plunger 40 and cam plate 68is rigidly held in adjusted position on the cylindrical bar 46 by meansof a set screw 78 screw threaded through a lug 80 in the cam plate 68for engagement with one of a series of indents 82 in the surface of thecylindrical bar 4 6.

Adjustment of the vertical position of the drag blade 34 is effected byvarying the angular position of the blocks 42 on the cylindrical bar 46in the following manner:

Assuming that the blocks 42 are adjusted in a clockwise direction fromthe full-line position shown in FIG. 1, the movement of the rollers 58on their cams 56 will permit a forward movementof the two plun-gers 40under the influence of springs 60 to maintain the tubular member 36upper edge of the drag blade 34 in the desired position of adjustmentwith respect to the traveling web. At the same time the movement of thepost 76 and roll 74 with relation to the cam extension 72 will controlthe angular position of the tubular member 36 and drag blade 34 tomaintain the lower edge of the drag blade in the desired spaced relationto the traveling web and blade. The roller 74 is held against its cam 72by any convenient means as, for example, a spring 84 tensioned between apin 86 on the upper side of the tubular member 36 and a pin 88 on thesplit clamp 48. If no such biasing spring is provided, the forcesgenerated by the rapidly moving web which include air suction betweenthe web and the inner surface of the drag blade, and the eddy currentsinduced in the liquid within the reservoir may be expected to maintainthe drag blade in approximately the desired position.

The drag blade 34, located in close proximity to the rapidly moving web,has the affect of shielding the web from the coating material in theenclosure over an area which extends from the level at which the webpasses below the surface level of the liquid coating to the level of theemergence of the web from behind the bottom edge of the drag blade 34.With this arrangement a pull is exerted upon the liquid coating 22 onlyduring the short extent of travel of the web from the line of itsemergence from beneath the drag blade 34 to the line of engagement withthe doctor blade at the bottom tip of the en closure. The liquid is thuscaused to circulate in a manner which completely avoids the turbulence,splattering, and uneven pulling action which results when the rapidlymoving web is brought directly into contact with the surface of theliquid coating.

An upward or downward adjustment in the position of the drag blade 34has the effect of correspondingly varying the drag length during whicha. pull is exerted on the liquid coating by the traveling web. Aplurality of adjusted positions of the drag blade are shown in FIG. 3,said different positions of the drag blade 34 being indicated by thecharacters x to x inclusive. It will be noted that with each upwardadjustment of the drag blade there is a tendency for a greater amount ofthe liquid material drawn down to be forced under pressure against thetop face of the doctor blade 28. As the weight of the liquid materialbeing forced against the blade 28 increases, the blade is caused to bendoutwardly thus increasing the thicknesses of the resulting coat.

An alternative embodiment of the invention is shown in FIG. 4 of thedrawings in which the coater head designated at 90 is engaged againstthat portion of the web 22 which is directly beneath the backing roll20. The liquid coating supplied to the enclosure through inlet 92 inthis case is maintained under some pressure which insures an intimatecontact of the coating with the traveling web between the tip edge ofthe drag blade 94 and the edge of the doctor blade 96. In this form ofthe apparatus the drag blade 94 extends from without the within the areaoccupied by the liquid coating enclosure, and is supported on arms 97pivoted upon and extending radially from the axis of the roll 20. A seal98 interposed between the underside of the drag blade and the enteringedge of the enclosure prevents leakage of the coating at this point. Asshown in FIG. 4 the surface of the liquid and the entering edge of theenclosure 90 coincide. traveling web exerts a drag upon the liquidcoating which extends from the terminal edge of the drag blade 94 to thepoint of engagement with doctor blade 96 The liquid in the enclosure isthus put in motion traveling in a circular path which is substantiallyfree from turbulence so that the liquid is forced evenly and underconstant pressure against the face of the doctor blade. In this form ofthe device, the surface of the liquid and the entering edge of theenclosure coincide. The adjustment of the forward and back position ofthe drag blade 94 about the axis of rotation of the backing roll 20 iscontrolled by angular adjusting of the supporting arms 97 The,

about the rotational axis of the backing roll 20, and has the effect ofcorrespondingly varying the weight of the liquid coating forced againstthe inner face of the doctor blade and consequent thickness of thecoating applied to the web.

Still another application of the drag blade in accordance with thepresent invention is shown in FIG. 5, in which there is shown a backingroll 1% which provides support for the traveling web 22. For applying acoating to the web 22 there is provided a coating roll 1114 which ismounted in parallel relation to the backing roll 100 in a position toprovide a liquid coating applying hip to the web 22. A pool of liquidcoating 106 is formed above and beneath the two rolls. FIG. is intendedonly as a diagrammatic disclosure of the modification. It will beunderstood that dikes of ordinary description such as that shown at 32in FIG. 2, but contoured to fit between the rolls 1% and 164 assuggested at 107 in FIG. 5 may be employed to close in the ends of thepool. In this form of the apparatus two drag blades -8, .111 areprovided, the drag blade 1% being supported on arms 112 pivoted on axis114 of roll 1% to be located in close proximity to the traveling web 22and backing roll 1% in such a position that it extends from above thelevel of the liquid pool 1116 to beneath the surface thereof. The dragblade 1111 is mounted to extend across the width of the coating roll 164in close proximity thereto and similarly extends downwardly into theliquid coating from a point substantially above the surface thereof. Thedrag blade 114i is mounted on arms 116 carried on the axis 118 for thecoating roll 1134. In this form of the device the thickness of thecoating applied to the traveling web will depend on the up and downadjustment of each of the two drag blades 1138, 110.

FIGS. 6, 7 and 8 illustrate a further embodiment of the invention inwhich the drag blade is a flexible element, here shown as a very thingage steel blade, although the blade may consist of a nonself-supporting limp or pliable material such as sheet rubber or thelike. In FIGS. 68 the backing roll is designated at 130 and thetraveling web at 132. A liquid coating container 133 is provided whichconsists of doctor blade holder 134- secured to a transverse framemember 136, and a doctor blade 138 supported in the holder for trailingengagement with the underside of the backing roll 13% and traveling web132. The rear side of the liquid coating container is closed by apreferably resilient member 139 supported in a frame 14!) attached atits lower edge by a hinge 141 to the holder 134, and along its upperedge secured to a transverse frame member 142 which is mounted closelyadjacent the backing roll 130 and traveling web 132. The ends of theliquid coating container are closed by dikes 144 shown in FIG. 7. Liquidcoating is supplied to the liquid coating container 133 above describedby means of a pipe 145 connected at one end to an inlet 146 for the container and at its other end extending downwardly within a liquid coatingstorage tank 143. In the illustration shown the liquid coating issupplied to the container 133 under pressure, the tank 148 beingpressurized for this purpose by compressed air supplied through an inletpipe 150 from a supply source, not shown. Air pressure is controlled bya valve 152 in the air inlet line 150, and further by a safety valve 154fitted into the topof the tank.

In this form of applicants invention a very flexible thin gage steeldrag blade 156 is employed which is introduced through a narrow openingprovided between the back side of the container 133 and the travelingweb 132. The drag blade 156 is supported along its upper edge by atransverse holder 158 provided at intervals along its length with screwbolts 160 screw threaded to cooperating nuts 162 rotatably fitted inapertures provided in an offset upper edge portion 164 of the transversesupport 136. To prevent loss of the liquid coating through the openingat the upper edge of the transverse frame member 142,

a rubber bead or similar flexible sealing element 166 is provided,fitted into an angle provided between the trans verse frame member 142and the frame 140 for engagement against the outer face of the dragblade 156.

The direct engagement of the liquid coating with the exposed portion ofthe traveling web 132 between the lower edge of the drag blade 156 andthe point of engagement of the web with the doctor blade 138 gives riseto viscous drag forces and eddy currents which cause the flexible dragblade 156 to be pressed toward the back roll and web so that the contourof the inner face thereof tends to be conformed substantially to thepath of the traveling web. A depth adjustment of the drag blade into thecontainer to vary the width of web exposed to the liquid coating betweenthe lower edge of the drag blade and the doctor blade is effected byadjustment of the nuts 162. The withdrawal of the drag blade 156 to theposition of FIG. 8, for example, by substantially increasing the area ofthe traveling belt directly in contact with the coating fluid, willincrease the downward flow of fluid and correspondingly increase thedeflection of the doctor blade 138. Further control of coat thickness iseffected by variation in the air pressure at the valve 152 which thusincreases or decreases, as the case may be, the fluid pressure withinthe liquid coating container 133, and correspondingly the mass of theliquid coating which is forced by the doctor blade 138. With theseadjustments, required adjustments and corrections in the flow andthickness of coating deposited on the web can be made readily duringcontinued operation of the coater.

FIG. 9 illustrates a further modification of the invention in which thehighly flexible drag blade 156, secured along its upper edge to thetransverse bar holder 158, is supported from without to extend within abody of liquid coating contained in an open container 174 located at oneside of the backing roll and traveling web 132. The container 174comprises the doctor blade holder 134 and doctor blade 138 secured to atransverse frame member 176, and end dikes which may be similar to thoseshown at 144- in FIG. 7. The drag blade 156 and holder 158 are suspendedfrom a bent over edge 17 8 of the transverse frame member 176 by meansof screw bolts 160, pivotally connected with the bar holder 15% of thedrag blade 156, and screw threaded toward their upper ends throughrotatable nuts 162 rotatably supported in apertures in the bent overedge 178.

The highly flexible drag blade 156, suspended as shown in FIG. 9 andalso as shown in FIGS. 6-8, extends from outside beneath the surface ofthe liquid in the liquid coating container 133, is disposed in narrowlyspaced parallel relation to and closely adjacent the traveling webacross the width of the opening in the container, and is acted upon insuch a manner by the traveling web and liquid currents set up in thecontainer that the contour of the face of the drag blade is conformedsubstantially to the path of the back roll supported web. The rapidmovement of the web 132 causes an air draft to be introduced between theweb and the drag blade 156 producing an air film, which, although it maybe only a few millionths of an inch in thickness, will cushion the dragblade slightly away from the web and will also prevent liquid fromseeping under the bottom edge of the blade.

It will be understood that the flexible drag blade 156 may besubstituted for the heavier gage drag blade 34 in the liquid reservoirand doctor blade assembly of FIG. 1, and that said flexible blade whenso installed will operate in a manner similar to the drag blade 34 tocontrol turbulence and the thickness and quality of the coatingproduced.

It will be understood further that the invention in its broader aspectsis not limited to the specific embodiments shown and that modificationsmay be made within the spirit and scope of the appended claims in theprecise composition, shape and surface texture of the drag blade 7supported adjacent the traveling web at the point of entry into the bodyof liquid coating to shield said entering portion of the web, so thatonly a submerged portion of the traveling web extending from the loweredge of the drag blade to the leaving edge of the container defined bythe yieldable trailing edge of the doctor blade is in contact with theliquid coating.

The invention having been described what is claimed is:

1. In a coater having a backing roll around which a traveling web to becoated is drawn, a liquid coating reservoir and doctor blade assemblywhich comprises a liquid coating enclosure having an open face disposedagainst said web and supporting backing roll; a trailing type doctorblade forming a base portion of said enclosure and having the trailingedge thereof yieldably supported with relation to said traveling web inposition closing the leaving edge of said open face; a drag bladedisposed in narrowly spaced relation to said traveling web across thewidth of the web and having the face thereof conformed generally to theweb and backing roll over which the web passes; said drag bladeextending from above the top face of said liquid coating material andterminating in an inner submerged edge spaced from said doctor bladethus forming a wall of said enclosure and generally preventing contactof said material with the traveling web portion contiguous to said dragblade so that substantially that portion only of the traveling Webextending from said inner submerged edge of the drag blade to theleaving edge defined by said doctor blade is in contact with said liquidcoating; and adjustable supporting means on which said drag blade isshiftable relatively to said backing roll to vary the width of the spacebetween the inner submerged edge of the drag blade and the doctor bladeand thereby the thickness of coating material driven past the yieldabletrailing edge of said doctor blade.

2. In a coater having a backing roll around wh ch a web to be coated isdrawn, the combination of a liquid coating reservoir and doctor bladeassembly according to claim 1 in which the drag blade is a rigidlyformed self-supporting element having a face adjacent said web contouredsubstantially to the curvature of the traveling web,

3. In a coater having a backing roll around which a web to be coated isdrawn, the combination of a liquid coating reservoir and doctor bladeassembly according to claim 1 in which the drag blade is a flexible andpliable element which tends to be conformed to the curved traveling webby forces set in motion by the traveling web.

4. In a coater having a backing roll around which a web to be coated isdrawn, the combination of a liquid coating reservoir and doctor bladeassembly according to claim 3 in which the drag blade is a thin flexiblemetallic element which tends to be conformed to the curved traveling webby forces set in motion by the traveling web.

5. For use in a coater having a backing roll around which a travelingweb to be coated is drawn, and a liquid coating reservoir and applicatorassembly which comprises, in combination, a. liquid coating enclosurehaving an open face disposed against said web and supporting backingroll; and a liquid coating applicator disposed upon the leaving edge ofsaid liquid coater; a drag blade disposed in narrowly spaced parallelrelation to said traveling web of a length to extend across said web,and curved to substantially the radius of curvature of said web, saidblade entering the surface of the liquid coating from the entering sideof said enclosure and terminating beneath the surface of said liquid ina lower edge spaced from said applicator thus forming a wall of saidenclosure and generally preventing contact of said material with thetraveling web portion contiguous to said drag blade; and a supportassembly for said drag blade comprising a plurality of supportingstructures having a common rotational axis fixed with relation to saidenclosure and parallel to the axis of said backing roll, each saidstructure comprising a plunger pivotally connected at its outer end withsaid drag blade, a sleeve support block rotatably adjustable on saidaxis providing a sleeve support for said plunger, a cam followersupported on said plunger in combination with a cam fixed with relationto said enclosure, said cam and follower being conformed for any angularadjustment of said sleeve support to effect a corresponding movement ofthe lunger axially as it is carried through said angular adjustment andtending to thereby impart to the drag blade a resultant compoundmovement; and cam and follower connections between said plunger and dragblade conformed for any said combined axial pivotal movement of saidplunger to maintain constant said closely spaced parallel relationshipof the blade to the peripheral surface of the backing roll, the dragblade thus having a total movement which is arcuate with respect to thetraveling web contiguous therewith and the backing rolls.

6. In a coater having a backing roll around which a web to be coated isdrawn, and a drag blade according to claim 1, the combination of havinga liquid reservoir and doctor blade assembly pivotal supporting meanscoaxial with said backing roll axis on which said drag blade isshiftable arcuately about the backing roll axis to vary the width ofsaid space and thereby the thickness of coating material driven past thetrailing edge of said doctor blade.

'7. In a liquid material applying coater having a backing roll aroundwhich a web to be coated is drawn, and a liquid coating reservoir andapplicator assembly which comprises a liquid coating enclosure having asone side of said enclosure the downwardly drawn web and supportingbacking roll according to claim 1 the combination, in which the oppositeside of said enclosure comprises an opposed liquid applying rollproviding a liquid coating applying nip against a downwardly movingportion of the backing roll supported web, and a second drag bladesimilarly disposed in narrowly spaced relation to and closely adjacentsaid liquid applying roll extending from above the top face of andterminating beneath the surface of said liquid coating.

8. In a coater having a backing roll around which a web to be coated isdrawn according to claim 1, the combination of dikes closing the twoends of said open face, and a resilient sealing element closing the webreceiving edge of said open face, the drag blade is a flexible dragblade disposed across the width of said web extending between saidresilient sealing element and web from outside the body of said liquidand terminating beneath the surface of the liquid with the submergedportion of said drag blade substantially conformed to the curvature ofthe traveling web and backing roll and with the submerged edge of saiddrag blade spaced from the doctor blade so that that portion only of theweb traveling across said open face is in contact with said liquidcoating, and a support to which the drag blade is attached externally ofsaid enclosure.

9. In a coater having a backing roll around which a web to be coated isdrawn, the combination of a liquid coating reservoir and doctor bladeassembly according to claim 8 in which means are provided for supplyingliquid coating under pressure to said enclosure.

10. In a coater having a backing roll around which a web to be coated isdrawn, the combination of a liquid coating reservoir and doctor bladeassembly according to claim 9, in which a portion of said enclosure isformed of resilient material in order to minimize pressure vari ationswithin said enclosure.

(References on following page) UNITED 9 References Citefi by theExaminer 2,75 8,336 STATES PATENTS 2,855,895 3,018,757 Bergman 117*11 30 4 924 Francis 5 3 1 Francis 118-413 X Ward 117-115 X Franssen 118415 XBurns et a1. 118407 Loppnow 118-262 Stack 101-364 X Eolkin et a1 118-7 XMORRIS KAPLAN, Primary Examiner.

1. IN A COATER HAVING A BACKING ROLL AROUND WHICH A TRAVELING WEB TO BECOATED IS DRAWN, A LIQUID COATING RESERVOIR AND DOCTOR BLADE ASSEMBLYWHICH COMPRISES A LIQUID COATING ENCLOSURE HAVING AN OPEN FACE DISPOSEDAGAINST SAID WEB AND SUPPORTING BACKING ROLL; TRAILING TYPE DOCTOR BLADEFORMING A BASE PORTION OF SAID ENCLOSURE AND HAVING THE TRAILING EDGETHEREOF YIELDABLE SUPPORTED WITH RELATION TO SAID TRAVELING WEB INPOSITION CLOSING THE LEAVING EDGE OF SAID OPEN FACE; A DRAG BLADEDISPOSED IN NARROWLY SPACED RELATION TO SAID TRAVELING WEB ACROSS THEWIDTH OF THE WEB AND HAVING THE FACE THEREOF CONFORMED GENERALLY TO THEWEB AND BACKING ROLL OVER WHICH THE WEB PASSES; SAID DRAG BLADEEXTENDING FROM ABOVE THE TOP FACE OF SAID LIQUID COATING MATERIAL ANDTERMINATING IN AN INNER SUBMERGED EDGE SPACED FROM SAID DOCTOR BLADETHUS FORMING A WALL OF SAID ENCLOSURE AND GENERALLY PREVENTING CONTACTOF SAID MATERIAL WITH THE TRAVELING WEB PORTION CONTIGUOUS TO SAID DRAGBLADE SO THAT SUBSTANTIALLY THAT PORTION ONLY OF THE TRAVELING WEBEXTENDING FROM SAID INNER SUBMERGED EDGE OF THE DRAG BLADE TO THELEAVING EDGE DEFINED BY SAID DOCTOR BLADE IS IN CONTACT WITH SAID LIQUIDCOATING; AND AJUSTABLE SUPPORTING MEANS ON WHICH SAID DRAG BLADE ISSHIFTABLE RELATIVELY TO SAID BACKING ROLL TO VARY THE WIDTH OF THE SPACEBETWEEN THE INNER SUBMERGED EDGE OF THE DRAG BLADE AND THE DOCTOR BLADEAND THEREBY THE THICKNESS OF COATING MATERIAL DRIVEN PAST THE YIELDABLETRAILING EDGE OF SAID DOCTOR BLADE.